1. Field of the Invention
This invention relates to instruments for measuring the frequency and power of a microwave signal.
2. Description of the Related Art
One known such instrument comprises an input port for receiving the microwave signal, means for down-converting the microwave signal to an intermediate frequency signal, and means for measuring the frequency and power of the intermediate frequency signal thence to provide, after taking into account the down-conversion, a measure of the frequency and power of the microwave signal.
A problem with this known instrument is that the frequency and power measurements are performed on an intermediate frequency signal derived from the microwave signal, and not the microwave signal itself. This leads to inaccuracy in the measurement of the power of the microwave signal. The down-conversion is made in the known instrument in order to avoid the difficulties associated with making simultaneous frequency and power measurements on a microwave frequency signal.